The design problem has resulted in the facility’s roof needing to be elevated another 13 feet in order to fit all of the equipment and other contents planned for the uranium facility.

Construction of the building has not begun, but this problem has caused the project’s “phase one” completion date to be pushed back another five years, from 2020 to 2025. While the facility is slated to be “operational” by that date, it is not expected to be fully equipped until 2038.

The revised timetable has raised concerns about the safety of the plant’s World War II-era 9212 uranium processing complex, which the new UPF is designed to replace. The old complex is said to be deteriorated, with upgrading to current standards deemed impossible. Operations in that structure have been described as inconsistent, with repeated equipment failures. It also no longer meets safety requirements or seismic codes.

The NNSA has not responded to media questions regarding worker safety at the old complex, according to Frank Munger of the Knoxville News Sentinel. The delay now means that the dilapidated facility will have to operate for another 12 years.

In a 2009 interview with the newspaper, Y-12’s then-general manager, Darrel Kohlhorst, said that if a replacement complex was not built and operational between 2018 and 2020, “you may be out of luck. Because there’s going to become a trigger point where the infrastructure, where this facility, is just not safe to continue operating.”

When it was first proposed, the project was expected to cost a total of $1.1 billion to complete. Now, that figure has soared to $6.5 billion, and the cost might increase further because the roof revision burned through nearly half of NNSA “contingency” funds, the GAO found.